Expirmemntal memory save

Author: aidankeefe2022

wolfcrypt/src/wc_mlkem_poly.c

@@ -4379,24 +4379,18 @@ static void mlkem_get_noise_x3_eta2_aarch64(byte* rand, byte* seed, byte o)
  */
 static void mlkem_get_noise_x3_eta3_aarch64(byte* rand, byte* seed, byte o)
 {
-    word64 state[3 * 25];
-
-    state[0*25 + 4] = 0x1f00 + 0 + o;
-    state[1*25 + 4] = 0x1f00 + 1 + o;
-    state[2*25 + 4] = 0x1f00 + 2 + o;
-
-    mlkem_shake256_blocksx3_seed_neon(state, seed);
-    XMEMCPY(rand + 0 * ETA3_RAND_SIZE, state + 0*25, SHA3_256_BYTES);
-    XMEMCPY(rand + 1 * ETA3_RAND_SIZE, state + 1*25, SHA3_256_BYTES);
-    XMEMCPY(rand + 2 * ETA3_RAND_SIZE, state + 2*25, SHA3_256_BYTES);
-    mlkem_sha3_blocksx3_neon(state);
-    rand += SHA3_256_BYTES;
-    XMEMCPY(rand + 0 * ETA3_RAND_SIZE, state + 0*25,
-        ETA3_RAND_SIZE - SHA3_256_BYTES);
-    XMEMCPY(rand + 1 * ETA3_RAND_SIZE, state + 1*25,
-        ETA3_RAND_SIZE - SHA3_256_BYTES);
-    XMEMCPY(rand + 2 * ETA3_RAND_SIZE, state + 2*25,
-        ETA3_RAND_SIZE - SHA3_256_BYTES);
+    word64 state[30];
+    byte i;
+
+    for (i = 0; i < 3; i++) {
+        state[4] = 0x1f00 + i + o;
+        mlkem_shake256_blocksx3_seed_neon(state, seed);
+        XMEMCPY(rand + i * ETA3_RAND_SIZE, state, SHA3_256_BYTES);
+        mlkem_sha3_blocksx3_neon(state);
+        rand += SHA3_256_BYTES;
+        XMEMCPY(rand + i * ETA3_RAND_SIZE, state,
+            ETA3_RAND_SIZE - SHA3_256_BYTES);
+    }
 }
 
 /* Get the noise/error by calculating random bytes.